Instruments are used in industrial applications to control processes. For example, instruments can be used to measure characteristics of materials flowing through a pipeline, processes running in a chamber, monitor environmental conditions, etc. The instruments can provide data of the measurements through, for example, an interface that is accessible by an operator. Using the data provided by the instruments, other devices such as valves, pumps, motors, or the like can be operated to control other processes. The data can also be used for analysis, sorting the fluid, compensating for environmental conditions, or the like.
The instrument can be employed in various industrial applications and settings. As a result, the instrument is often required to meet a wide range of environmental specifications. For example, the instrument may be required to reliably function in high humidity while being subjected to temperature cycles or corrosive environments. The instrument might also be required to accept data input in these environments. For example, an operator working on the pipeline may be required to input data into the instrument under various environmental conditions. To input the data, the operator typically presses buttons on an interface.
The buttons can be comprised of infrared buttons with light sensors that detect changes in light intensity due to the presence of an object, such as a finger. The infrared buttons are typically calibrated to operate in both high and low temperature environments. However, the calibration routines are typically done with standards that do not necessarily include tolerances that are found in the interface. For example, a standard distance of the finger from a standard intensity light beam is sometimes employed. As a result, tolerance stack-ups and product-to-product variations can introduce errors in the data input through prior art buttons. In addition, the stack-ups and variations can cause the buttons to feel inconsistent to the operator, which can also introduce data errors or cause delays in the data entry.
Although the reliability of the touch sensors can be improved by configuring the touch sensors for specific products, such custom configurations are expensive and prone to introducing additional defects into the product. Accordingly, there is a need for an interface with an adaptive reflected light touch sensor.